Tissue expanders, implants, and methods of use

ABSTRACT

Tissue expanders and methods of use. In some embodiments the tissue expanders are adapted to reduce wear on one or more components.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/389,222, filed Dec. 22, 2016, which is a continuation of U.S.application Ser. No. 14/186,985, filed Feb. 21, 2014, now U.S. Pat. No.9,526,584, which application claims the priority of U.S. Prov. App.61/767,754, filed Feb. 21, 2013 and U.S. Prov. App. 61/767,758, filedFeb. 21, 2013, the disclosures of which are incorporated herein byreference.

This application is related to and incorporates herein by reference thedisclosures of the following applications: U.S. Pub. No. 2011/0152913,published Jun. 23, 2011; U.S. Prov. App. No. 61/288,197, filed Dec. 18,2009; U.S. Pub. No. 2006/0069403, published Mar. 30, 2006; U.S. Prov.App. No. 60/612,018, filed Sep. 21, 2004; and U.S. Prov. App. No.60/688,964, filed Jun. 9, 2005.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

BACKGROUND

A deficit of normal tissue in a subject may result from, for example,burns, tumor resection surgery (e.g., mastectomy), or congenitaldeformities. Often, the tissue in deficit is skin and/or underlyingconnective tissue. The tissue in deficit can also be an intrabody duct(e.g., urethras or GI tract).

One method of correcting skin deficit is to stimulate creation of newskin. Implantation of a device that expands and stretches the existingskin causes a growth response in which new skin is created.

The first report of tissue expansion was in 1956 by Charles Neumann(Plastic & Reconstructive Surgery; Vol 19 (2); 124-130) who implanted arubber balloon attached to a percutaneous tube to enable intermittentexpansion for the purpose of reconstructing a partially amputated ear.Since that time, the idea of tissue expansion devices has undergonecommercial development.

Most commercially available tissue expanders function as an implantableballoon with an extracorporeal or imbedded valve that allows periodicinflation. Typically, it is a doctor that performs the inflation. Sincethe inflation events are relatively infrequent, a significant inflationpressure is typically applied at each doctor's visit in order to achievemaximum effect from each visit. As a result of this inflation pressureduring a clinic visit, a relatively sudden tissue stretch occurs. Thismay cause subjects to suffer discomfort and/or tissue ischemia. Therelatively large inflation pressure can also adversely affect underlyingstructures (e.g., cause concavities in underlying bone). In addition,high pressure may create restrictive capsules around the implant and/orcause tissue failure. Some previously available alternatives used aneedle for inflation or filling, creating a potential source ofinfection.

In order to overcome such issues, continuously expanding devices havebeen developed. For example, osmotic expanders have been reported byAustad in 1979, Berge in 1999, and Olbrisch in 2003 (see U.S. Pat. Nos.5,005,591 and 5,496,368). A commercial version is available from OsmedCorp. in a limited range of sizes. These devices use a polymeric osmoticdriver to expand a silicone implant by absorbing interstitial fluid(ISF). A potential problem of such devices is the lack of control oradjustability after implantation with respect to expansion variablessuch as pressure, volume, onset of expansion, and end of expansion oncethey have been deployed.

U.S. Pat. No. 6,668,836 to Greenberg et al. describes a method forpulsatile expansion of tissue using an external hydraulic pump. Theexternal hydraulic pump is bulky and may lead to negative subjectreactions. The percutaneous attachment reduces subject mobility and maybe a source of contamination. U.S. Pat. No. 4,955,905 to Reed teaches anexternal monitor for pressure of an implanted fluid filled tissueexpansion device. U.S. Pat. Nos. 5,092,348 and 5,525,275 to Dubrul andIverson respectively teach implantable devices with textured surfaces.U.S. Patent Publication No. 2004/0147953 by Gebedou teaches a devicewhich relies upon an internal mechanical force as a means of avoidinguse of fluids for tissue expansion. U.S. Pat. Nos. 6,264,936; 6,180,584;6,126,931; 6,030,632; 5,869,073; 5,849,311 and 5,817,325 deal generallywith the concept of antimicrobial coatings.

The disclosure herein describes tissue expanders and methods of use thatovercome shortcomings of existing tissue expanders.

SUMMARY OF THE DISCLOSURE

One aspect of the disclosure is a tissue expander comprising animplantable portion comprising a fluid source in communication with anexpandable chamber, a first deformable member, a second deformablemember, and a lubricious material disposed between the first and seconddeformable members to reduce friction between the first and seconddeformable members.

In some embodiments the first deformable member at least partiallydefines the expandable chamber. The second member can be disposedoutside of the expandable chamber. The second deformable member can beconfigured as a barrier layer to the fluid and is disposed outside ofthe expandable chamber.

In some embodiments the tissue expander further comprises an outer shelldisposed at least partially around the first and second deformablemembers. The outer shell can be an elastic shell.

In some embodiments the first and/or second deformable members havepre-formed configurations, and either can include an inelastic materialwith the pre-formed configuration. The first and second deformablemembers can have pre-formed configurations that are substantially thesame.

In some embodiments the first and second deformable members arethin-walled deformable members. The first deformable member can bedisposed inside the second deformable member, and the first deformablemember can have a thickness between about 75 microns and about 150microns. The second deformable member can have a thickness between about25 microns and about 75 microns. The first deformable member can bedisposed inside the second deformable member, and the second deformablemember can have a thickness between about 25 microns and about 75microns. The first deformable member can be disposed inside the seconddeformable member, and the first deformable member can have a thicknessthat is about 1.5 to about 8 times the thickness of the seconddeformable member.

In some embodiments at least one of the first and second deformablemembers comprises multiple layers of material secured together.

In some embodiments the lubricious material has a viscosity of at least50 cP.

In some embodiments the lubricious material is a biocompatiblelubricant, such as a silicone-based lubricant.

In some embodiments the first deformable members is attached directly tothe second deformable member, and the first and second deformablemembers can be secured to each other at respective peripheries of thefirst and second deformable members.

In some embodiments the expandable chamber includes an anterior portion,wherein the anterior portion includes the first and second deformablemembers. The expandable chamber can include a posterior backing coupledto the first deformable member.

In some embodiments the first deformable member has a communicationcomponent secured to it, wherein the communication component isconfigured for wireless communication with an external controller.

In some embodiments the volume of lubricious material disposed betweenthe first and second members is between about 0.5 mL and about 2.5 mL,and can be between about 0.5 mL and about 2.0 mL.

In some embodiments the tissue expander further comprises an externalcontroller adapted to be in communication with the implantable portionto enable fluid to be released from the fluid source into the expandablechamber.

In some embodiments the lubricious material comprises a coating on atleast one of the two members.

In some embodiments the lubricous material provides substantially noadditional thickness to the implantable portion.

One aspect of the disclosure is a tissue expander comprising: animplantable portion including an expandable chamber in fluidcommunication with a fluid source; a first deformable member at leastpartially defining the expandable chamber and having a pre-formedconfiguration; a second deformable member disposed about the firstdeformable member; and an outer shell disposed about the first andsecond deformable members.

In some embodiments the second deformable member has a pre-formedconfiguration. The first and second pre-formed configurations can besubstantially the same.

In some embodiments the first and second deformable members form atleast part of a gas barrier layer of the implantable portion that issubstantially impermeable to fluid in the fluid source.

In some embodiments the outer shell is an elastic shell.

In some embodiments the first and second deformable members arethin-walled deformable members.

In some embodiment the first deformable member is disposed inside thesecond deformable member, and the first deformable member has athickness between about 75 microns and about 150 microns. The seconddeformable member can have a thickness between about 25 microns andabout 75 microns.

In some embodiments the first deformable member is disposed inside thesecond deformable member, and the second deformable member has athickness between about 25 microns and about 75 microns.

In some embodiments the first deformable member is disposed inside thesecond deformable member, and the first deformable member has athickness that is about 1.5 to about 8 times the thickness of the seconddeformable member.

In some embodiments the first deformable member has a communicationcomponent secured to it, wherein the communication component isconfigured for wireless communication with an external controller.

One aspect of the disclosure is a tissue expander comprising: animplantable portion comprising a fluid source in fluid communicationwith an expandable chamber, a communication element secured to theexpandable chamber and movable relative to the expandable chamber; andan external controller configured for wireless communication with thecommunication component to enable fluid to be released from the fluidsource into the expandable chamber.

In some embodiments the communication element is an antenna.

In some embodiments the communication element is stiffer than theexpandable chamber.

In some embodiments the expandable chamber has a thickness between about50 microns and about 150 microns.

In some embodiments the communication element is disposed inside apocket, and the pocket is attached to the expandable chamber. Thecommunication element can be secured inside the pocket such that itfloats inside the pocket. Two sides of the pocket can be attachedtogether at a plurality of discrete locations with at least oneunattached location between the two sides. The pocket can be attached tothe expandable chamber at a plurality of discrete locations with atleast one unattached location where the pocket is not attached to theexpandable chamber. The pocket can be secured to the expandable chamberaround a periphery of the pocket at at least three locations withunsecured locations where the pocket is not attached to the expandablechamber.

In some embodiments the communication element is secured to a firstportion of the expandable chamber that, in a side view of an expandedconfiguration of the expandable chamber, is less curved than a secondportion of the expandable chamber.

In some embodiments the expandable chamber comprises an inelasticmaterial with a preformed expanded configuration, and the communicationelement is secured to the inelastic material such that it can moverelative to the inelastic material.

One aspect of the disclosure is a device adapted to be implanted in thebreast, comprising a deformable chamber with a gel disposed therein; adeformable member at least partially surrounding the deformable chamber;and a lubricious material disposed between and in contact with thedeformable chamber and deformable member.

In some embodiments the deformable chamber and deformable member arecomprised of an elastic material.

In some embodiments the volume of lubricious material is less than about5 mL, less than about 4 mL, less than about 3 mL, less than about 2 mL,or less than about 1 mL.

In some embodiments the lubricious material comprises a coating on atleast one of the deformable chamber and deformable member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an exemplary tissue expander system including aremote controller and an implantable portion.

FIGS. 1B and 1C illustrate an exemplary implantable portion of a tissueexpander system.

FIG. 1D illustrates a sectional view of an exemplary implantable portionof a tissue expander system.

FIG. 2 illustrates an exemplary tissue expander system including aremote controller and an implantable portion.

FIGS. 3 and 4 illustrate an exemplary exploded view of a backing anddriver of an exemplary implantable portion of a tissue expander system.

FIG. 5 is an exploded view of an exemplary implantable portion includingan outer shell disposed around an inner bag, or inner portion.

FIG. 6 illustrates an exemplary implantable portion, with a sectionremoved to visualize a portion of the expandable chamber.

FIG. 7 is an exploded view of a communication component and an anteriorlayer of an exemplary implantable portion.

FIGS. 8A and 8B illustrate the assembled communication component andanterior layer from FIG. 7.

FIG. 9 is an exploded view of an inner portion of an exemplaryimplantable portion. The inner portion includes an inner member and anouter member.

DETAILED DESCRIPTION

The disclosure describes tissue expanders and methods of using them toexpand tissue. In some embodiments of use the tissue expanders are usedto expand tissue and create a “pocket” within tissue, into which amedical device, such as a permanent implant, may be positioned. Forexample without limitation, the tissue expanders can be used to create apocket within breast tissue, into which a breast implant can bepositioned after removal of the tissue expander. Additional exemplaryuses are described in U.S. Prov. Appln. No. 61/767,758, filed Feb. 21,2013, incorporated by reference herein.

FIGS. 1A-1D illustrate an exemplary tissue expander, exemplary detailsof which are also described in U.S. Pub. No. 2006/0069403, publishedMar. 30, 2006. FIGS. 1A-1D illustrate a self-contained implantabletissue expansion device 300 that includes an expandable compartment 310.Device 300 includes a fill source, optionally a gas source 210. Device300 is configured as a breast tissue expander positionable in a breast610 of a subject. This may be undertaken, for example following surgeryperformed on breast (e.g., tumor resection). Optionally, device 300expands over a period of time via transfer of gas from gas source 210 toexpandable compartment 310. Device 300 can restore skin and/or muscletissue of the breast to dimensions similar to those of a contra-lateralbreast. Optionally, this facilitates implantation of a long termcosmetic implant in the breast so that the subject achieves approximatebilateral symmetry with the contra-lateral breast. Because gas can bepacked under pressure in a small volume and later expand to a largervolume at a lower pressure, device 300 may be self-contained.Alternatively or additionally, a device that will eventually assumelarge proportions may be collapsed and implanted through a smallincision.

In an exemplary embodiment, device 300 relies on a self-contained gassource 210. Optionally, source 210 contains a fixed amount of gas.Optionally, a fixed amount of gas makes unwanted over inflation less ofa safety concern. In an exemplary embodiment of the invention, the fixedamount of gas in source 210 corresponds to a desired maximum inflationof expandable compartment 310. This makes explosion of compartment 310as a result of sudden release of the contents of source 210 intocompartment 310 unlikely.

Gas source 210 optionally has an internal volume of 1 cc to 50 cc,optionally 2 to 10 cc. In an exemplary embodiment of the invention, acompressed gas source 210 has a total internal volume of about 5 ml.Optionally a large tissue expansion may be achieved by providing 2.5grams of CO₂ in a 5 ml internal-volume container. This provides about1200 ml of CO₂ at 15 PSI (1 PSI above atmosphere at sea level).Alternatively or additionally, a 0.05 ml CO₂ source could provide afinal volume of about 12 ml final volume. Optionally, many small gassources 210 are provided in a single device 300.

In an additional exemplary embodiment device 300 includes an expandablecompartment 310 adapted for implanting in a body of a subject and a gassource 210 coupled to said compartment; and at least one regulatoradapted to be located within said body and selectively control gas flowfrom said source to said compartment. Optionally, source 210 is adaptedto be external to a body of a subject and is connected by a tube tocompartment 310.

The release of gas from source 210 can be controlled over a period oftime. This contributes to a gradual inflation of compartment 310 whichcan reduce patient discomfort. Alternatively or additionally, morefrequent and/or continuous expansion events may reduce the likelihood ofthe development of a restricting capsule. Small gradual expansion ishypothesized to result in less capsule formation, i.e., reduced capsulethickness, than expansion brought about by greater expansive force(pressure). In an exemplary embodiment, a treatment with device 300according to the present invention might last 7 to 180 days, in someembodiments can be used in less than 1 month, and in some embodimentsbetween two and three weeks. Actual treatment time might depend uponfactors including, but not limited to, required degree of expansionand/or elasticity of tissue(s) to be expanded and/or growthcharacteristics of tissue to be expanded and/or subject compliance withtreatment.

In an exemplary embodiment, additional control over transfer of gas fromsource 210 to compartment 310 is achieved by flow restriction. Device300 optionally includes a valve, examples of which are described in U.S.Pub. No. 2011/0152913, published Jun. 23, 2011 and U.S. Pub. No.2006/0069403, published Mar. 30, 2006. The valve may optionally regulatea flow of gas under pressure from gas source 210 into expandablecompartment 310. An actuator may optionally apply additional regulationto valve 100. Exemplary actuators 200 are described in greater detail inU.S. Pub. No. 2006/0069403, published Mar. 30, 2006.

In an exemplary embodiment, a gradual expansion of tissue is desired.Optionally, gradual expansion indicates a period of several weeks,optionally several months, as much as six months or more. Optionally, alow rate of transfer of gas from gas source 210 to expandablecompartment 310 is employed. Optionally, a valve is characterized by alow flow rate. Optionally, regulation of a flow rate through valve 100is desired. Optionally, an actuator is included in device 300.

In an exemplary method of use, device 300 is employed as part of amethod of repair after a tissue damage event has occurred. Tissue damagemay be, for example, a tumor resection, such as a mastectomy.Optionally, modeling of the affected tissue is performed prior to tissuedamage. Optionally, modeling of a matching contralateral tissue (e.g.,breast) is performed. Device 300 is prepared optionally based on themodeling. Optionally, device 300 includes thermoplastic or thermosettingsections that are shaped during modeling. Optionally modeling includescalculation of a required incremental inflation volume and/or pressurethat may be translated to an amount of a specific inflation gas ingrams.

After preparation, device 300 is implanted. After implantation, device300 expands over a period of time by transfer of gas from source 210 tocompartment 310 causing tissue expansion. Optionally this process may beregulated or controlled as detailed herein. Once tissue expansion iscomplete, removal of device 300 may be performed, for example to implanta replacement long term implant. Optionally, device 300 is madepermanent, for example by filling with a conventional implant materialsuch as, for example, silicone gel or saline.

In another exemplary embodiment, tissue expansion device 300 isoptionally employed to grow new skin to permit repair of damaged skintissue at another location. Modeling is optionally not pursued in theseuses because the device can disrupt a natural body contour as a means ofcreating excess skin for subsequent transfer. New skin may be induced togrow by increased tension resulting from expansion of the implanteddevice as described hereinabove. Optionally, the new skin is harvestedand transferred to a new location as an autologous graft. In anexemplary embodiment of the invention, this strategy is employed toeffect cosmetic repair. Optionally, the cosmetic repair may be for scarremoval, to replace a tattooed area, to replace skin damaged by burns orto ameliorate pigment irregularities. Optionally, skin for transfer iscreated in a matching body area. For example, repair of a right side ofthe face might be pursued by implanting a device under the left cheek.Optionally, this might produce skin with similar characteristics to thedamaged skin in terms of pigment and/or elasticity and/or hairprevalence and/or hair characteristics. According to these embodimentsof the invention, a subject may voluntarily undergo a short termdisfigurement in order to overcome long term tissue damage. In anexemplary embodiment of the invention, new skin is molded. Optionally,molding occurs during formation. Optionally, molding occurs during orafter transplant. Optionally, molding is in conformation to a formattached to the device. Optionally, molding is in conformation to a formprovided at a transplant site. In an exemplary embodiment of theinvention, new skin grown in response to pressure provided by a deviceis employed to reconstruct an ear.

An inelastic shell may optionally include film laminates such as, forexample, metalized Mylar (PET) (e.g., MC2-100; DuPont Teijin FilmsHopewell, Va., USA) or metallized nylon or other metallized polymerfilms that may act as gas diffusion barriers, or a laminate ofpolypropylene, polyethylene or nylon as an outer skin with an inner gasbarrier of poly(vinylidene chloride) and a polyethylene inner layer usedfor thermally bonding the film made by Dow Chemical Co. (for example,XUR-1689, Midland, Mich., USA) are suitable for use in the invention. Inan exemplary embodiment of the invention, the inelastic shell is shapedby folding, optionally pleating or accordion folding.

Optionally, the inelastic shell is installed inside the elastic balloonso that accordion like unfolding of the inner shell is less apparentfrom outside. Optionally, one layer controls gas diffusion and/orimparts a desired shape. Optionally, one layer regulates expansion byproviding a resistive force.

Optionally, the expandable compartment provides a natural body contourand/or natural feel. This may be accomplished, for example, by using atarget tissue to model the compartment. For example, a breast prior totumor resection, and/or a contralateral breast might be measured and/orcast to provide appropriate dimensions and/or aspect rations for theimplantable portion of the tissue expander.

Alternatively or additionally, an inelastic shell may provide punctureand/or leak protection.

Optionally, total gas leakage from the expandable compartment is lessthan 5 ml/day, optionally less than 1 ml/day optionally about 0.11ml/day. In an exemplary embodiment of the invention, the gas is selectedto provide a desired leakage rate in combination with materials used toconstruct the expandable compartment. Desired rates may be achieved, forexample, with film laminates as described hereinabove. Sealing of aMylar shell of this type may be accomplished, for example, byapplication of heat and pressure using a commercially available heatsealer such as the one suitable for tray sealing for medical devicepackaging. For example, a 5 mm seal may be created by applying a 150degree centigrade heating element with a pressure of 40 PSI for 1second. For industrial production, heating elements may be speciallyshaped to produce implants with desired configurations. Additionallyseals may be prepared by the use of an appropriate adhesive to allow forbonding of the sheets. Alternatively or additionally, inelastic sheetsof different sizes and/or shapes may be bonded together to pre-form theimplantable device. Optionally, a desired leakage rate is achieved bydevice by construction using materials with known leakage or permeationcharacteristics. This may be accomplished, for example, by employingmaterials with desired permeability and/or diffusion characteristics inconstruction of the expandable compartment. In an exemplary embodimentof the invention, carbon dioxide is employed for inflation of theexpandable compartment and small amounts of excess gas may be safelyvented from compartment within the body.

In an exemplary embodiment of the invention, a desired size andconformation of device 300 after expansion is known in advance. Becausethe total desired inflation volume of expandable compartment 310 isknown, source 210 of device 300 configured to provide the desired volumeby controlling an amount of gas loaded therein. Gas source 210 may befilled, for example, by using carbon dioxide at 800 PSI (roomtemperature) flowing through a 2 micron particulate filter intocapillary tube 140 surrounded by PEEK tube 142. Source 210 is purgedtwice with pressurized gas and placed in an ice bath. Carbon dioxide gascondenses into source 210 at a rate of about 0.02 g/s so that a 2.5 gramcharge of CO₂ may be achieved in just over 4 minutes. The exact amountof charge may optionally be determined by monitoring the extra weight ofsource 210. Once source 210 is filled, valve 100 may be attached.Attachment may be, for example, vial mated sets of threads on source 210and valve 100. Optionally, a low loss “normally closed” valve 100 isemployed and source 210 may be filled days, or even weeks, beforedeployment in the device. Optionally, an additional seal is employed toreduce gas loss through the valve during storage. Optionally, sources210 with desired increments of gas fill are prepared commercially andsupplied as components for installation in the device.

Optionally, compartment 310 leaks at a known rate. This means that ifinflation is carried out to the point of discomfort, gradual relief willoccur without any active intervention. Alternatively or additionally, apressure sensitive valve releases excess pressure from compartment 310.Optionally, release of excess gas is into the body and/or transdermal.

Alternatively or additionally, a release valve 323 (FIG. 1A) is providedto prevent excessive expansion pressure in compartment 310. Optionally,gas is released through valve 323. Optionally, gas is released into thebody. Optionally, gas is released through a percutaneous release valve.In an exemplary embodiment of the invention release port 323 is an overpressure relief valve 323. Over pressure condition inside the expanderoptionally cause release through valve 323 by mechanical means and/orthrough control implemented via a microprocessor.

Alternatively or additionally, a semi-rigid or rigid backing 301 may beincluded within, or bonded to, the expandable compartment 310 (see FIGS.1B and 1C). Backing 301 may, for example, provide an orientation oranchor within the body. Alternatively or additionally, backing 301 maydirect expansion of compartment 310 in a desired direction and/orprovide a fixed aspect. In an exemplary embodiment of the invention, abreast expansion device 300 includes a semi-rigid siliconized rubberdisc 301 that can be deployed between skin and muscle and/or among orbetween muscle fiber bundles and/or beneath a muscle layer (e.g.,pectoral muscles in breast reconstruction). This optionally preventsunwanted pressure on the ribs. Optionally, operative components of thedevice can be mounted on rigid disc 301 (FIG. 1B).

As depicted in FIGS. 1A-1D gas source 210 and/or valve 100 and/oractuator 200 may optionally be contained within expandable compartment310. This protects these components and/or gives a natural contour tothe body of the subject by concealing their rigid outlines.Alternatively or additionally, this configuration may make the subjectless aware of the presence of more rigid components of device 300 byusing expandable compartment 310 as a cushion. For example, a subjectattempting to grow new skin on their face (e.g., for autologous graft)may be fitted with a device 300 in their right cheek. If source 210and/or valve 100 and/or actuator 200 were installed adjacent tocompartment 310, the subject might feel these components, for examplewhile trying to sleep on the right side. By installing these componentsinside expandable compartment 310, they are hidden within an inflatablecushion and the subject becomes less aware of their presence.Optionally, inflatable cushion/compartment 310 permits the subject tofall asleep more easily. Similar considerations apply for breastexpansion embodiments.

In an exemplary embodiment of the invention, tissue expansionapplications which require small expansion volumes, sufficient fillingof source 210 may be achieved with a gas that remains in the gas phasein source 210. In an exemplary embodiment of the invention, a faceexpander 300 employs a small amount of gas. For these types of smallexpansion applications, gases that are both compressible andbiologically safe might be employed. Examples of compressiblebiologically safe gases include, but are not limited to, oxygen,nitrogen, argon, xenon and neon etc.

The subject in whom the device is implanted may control expansion of theexpandable chamber using an external control unit 350 (FIG. 1A).Optionally, the system includes a power source located in the externalcontrol unit, which can provide power to the implantable portion. In anexemplary embodiment, the subject presses a button 360 (FIG. 1A) onexternal control unit 350 to trigger an inflation event (e.g., byissuing an operational command). Optionally, a single activation signalto the actuator opens the valve for a preset amount of time (e.g., 3seconds), or a preset flow volume through the valve (e.g., 15 ml). In anexemplary embodiment, imposition of a finite limit on the response tothe activation signal can serve as a safety feature.

In an exemplary embodiment, the driver is in communication with acommunication component such as an antenna (e.g. an RF coil) 320 mountedon a wall of expandable compartment 310. Optionally, antenna 320 ismounted inside compartment 310 as shown in FIG. 1D. Optionally, this isaccomplished by sandwiching between 2 layers of material as pictured.Alternatively or additionally, connection 321 between antenna 320 andactuator 200 follows the contour of compartment 310. Optionally,anchoring studs 311 help insure that antenna 320 remains close to theskin surface and/or in a known location. Optionally, source 210 and/oractuator 200 are anchored to base 301 with retention straps 221, visiblein FIG. 1D.

A companion antenna 322 in controller 350 communicates with the antennain the implantable portion without a physical percutaneous link. Thesesignals may be from the device to the control unit and/or from thecontrol unit to the device. Optionally, the signal includes power and/ordata. In order to conserve power and/or to prevent accidental signaling,antennae 320 and 322 may be configured to work only over very shortdistances (e.g., 5 to 25 mm). Optionally, antennae 320 and 322 arecircular and function as coils with near field coupling. In an exemplaryembodiment of the invention, the control unit is small and portable andmay be operated by either a doctor or by the subject in whom the deviceis implanted. Alternatively or additionally, antenna 322 may includeinduction coils which may be used to power operative components ofdevice 300, such as actuator 200. This configuration can be used soexternal controller 350 provides a safe and reliable means ofcontrolling transfer of gas from the gas source 210 to expandablecompartment 310 by separating the power source from actuator 200. Thisassures that actuator 200 operates only when controller 350 is in closeproximity to device 300, thereby preventing accidental inflation ofcompartment 310 of device 300.

Optionally, it may be desirable for the implantable portion to impart anatural body contour, for example in breast reconstruction. Theexpandable chamber may be formed from a deformable inelastic materialwhich is pre-molded to a desired shape. This may be accomplished, forexample, by welding or vacuum molding two sheets of material together.Alternatively or additionally, pleats or folds may be used to impart adesired shape. Desired shapes optionally include partial spheres (e.g.,hemisphere), offset partial sphere or breast (tear) shaped.

In an exemplary embodiment of the invention, a studded surface isemployed for anchoring so that protruding studs penetrate the overlyingpectoralis muscle in order to prevent movement of the device withrespect to the muscle. Optionally, studs are installed on an anteriorsurface. Optionally, 1-500, optionally, 2-350, optionally 3 to 75,optionally 4 to 50, optionally 5 to 25, optionally 6-10 studs of 2-3 mmin height are sufficient for anchoring. In an exemplary embodiment ofthe invention, the small number of studs provides a desired degree ofanchoring but does not contribute to difficulty in removing the device.Optionally, the studs are resorbable. In an exemplary embodiment of theinvention, once a capsule has formed to stabilize the position of thedevice, the studs are resorbed.

FIGS. 2-6 illustrate exemplary additional embodiments of tissue expandersystems and methods of use, additional details of which are described inU.S. Pub. No. 2011/0152913, published Jun. 23, 2011.

FIG. 2 illustrates an exemplary embodiment of a tissue expansion system.Tissue expansion system 10 includes implantable portion 20 (alsoreferred to herein as “implant”) and remote controller 30. In thisembodiment the implantable portion has a general breast shape orconfiguration and is adapted for breast reconstruction following, forexample, mastectomy. Implantable portion 20 includes outer shell 22 andan inner portion (also referred to herein as an “inner bag”), whichcomprises anterior portion 23 and posterior portion 21. A portion of theouter shell and the anterior portion of the inner bag are shown removedto illustrate additional components of the implant. The inner bagdefines an expandable chamber, or compartment. Implant 20 also includesfluid reservoir and valve 24 (when combined are commonly referred toherein as a “driver”), as well as communication component 25. The driverand the communication component are positioned completely within theinner bag and secured thereto, either directly or indirectly. In FIG. 2driver 24 is secured to cradle 26, which is secured to posterior portion21 of the inner bag.

Tissue expansion system 10 also includes remote controller 30, which isgenerally adapted to wirelessly communicate with and provide power tothe implantable portion via communication device 25 to control therelease of fluid from the fluid reservoir into the expandable innerchamber. Remote controller includes housing 31, actuator 32, and output33. Actuator 32 is shown as an actuatable button, while output 33 isshown as a plurality of visual indicators (e.g., LEDs). The actuator inthe remote controller can be any other suitable actuator (e.g., a knob,a microphone adapted to receive a user's voice as input, etc.). Theoutput can provide any number of different types of output tocommunicate information, such as, for example, visual, audio, tactile,etc.

FIGS. 3 and 4 illustrate exploded views of a portion of an alternativeembodiment of an implantable portion. FIG. 4 illustrates in greaterdetail the alignment of the components of the assembly. FIG. 3illustrates generally the posterior portion of the inner bag and themanner in which the driver is secured thereto. The portion of implant 40illustrates a general “hammock” design which allows the driver to besecured to the implant but where it is not rigidly fixed to theexpandable chamber. This design provides for a greater degree ofmovement between the driver and the inner bag. The embodiment in FIG. 3also reduces the “height,” or projection of the driver in the anteriordirection. The portion of the implant shown includes film band 41,hammock 43, driver 46, posterior panel barrier film 47, posterior panel52, sheeting material 48, barrier ring 49, and outer patch 50. In amerely exemplary embodiment, the components are made of the followingmaterials: film band 41 is a polyethylene film; hammock 43, whichincludes film 44, is a polyethylene film, posterior panel barrier film47 is a polyethylene/polyvinylidene chloride (“PVDC”) film; sheetingmaterial 48 is a textured silicone material; barrier ring 49 is apolyethylene/PVDC film; and outer patch 50 is a silicone material.

In an exemplary assembly of the implant shown, ends 42 of film band 41are heat-staked to posterior panel barrier film 47 at seal areas 53(shown in FIG. 4). Seal area 45 of film 44 is heat-staked to posteriorpanel barrier film 47 at seal area 54. The heat-staking secures hammock43 to posterior panel barrier film 47. End 45 of hammock 43 issuperiorly positioned to allow driver 46 to “hang” within hammock 43.Barrier ring 49 is heat-staked to posterior panel 52 at the eight (8)seal areas 51 (only one is shown in FIG. 4), which secures siliconsheeting material 48 between barrier ring 49 and posterior panel 52.Outer patch 50 is secured to sheeting material 48 using siliconeadhesive. Once assembled the portion of the implant 40 can then besecured to the rest of the implant (e.g., the anterior portion of theinner bag and the outer shell).

In the embodiment shown in FIGS. 3 and 4, the height, or projection, ofthe driver is reduced. Because the driver is not rigidly fixed to theinner expandable compartment, it has more flexibility within theimplant. The position of the driver can be slightly adjusted relative toparts of the anatomy to relieve discomfort caused by the driver. Forexample, the driver can pivot, or rock, if it is located on top of abony rib, thereby reducing discomfort to the patient. This arrangementallows the driver to be secured to the expandable chamber without beingrigidly fixed thereto. While this design does provide for movement ofthe driver within the implant, film band 41 acts to prevent the driverfrom moving around too much due to patient movement (e.g., jumping,driving over bumpy terrain, etc.).

FIG. 5 illustrates an alternative embodiment of an implantable portion(driver and implant antenna not shown). The inner bag includes generallybreast-shaped anterior portion 65, which has a perimeter seal 66 with aserpentine cut that creates a plurality of fingers 67. The inner bagalso includes posterior portion 72, which also has a serpentine cutaround a perimeter seal to create a plurality of fingers 71. In anexemplary method of manufacturing, phone dial film 74 is heat staked toposterior portion 72 through phone dial 73. Hammock 69 and band 68 areheat staked to the inner surface of posterior portion 72 as in theembodiment in FIGS. 3 and 4. The perimeter of anterior portion 65 isheat staked to the perimeter of posterior portion 72, forming the innerexpandable chamber. The inner portion, once assembled, is then placedwithin outer shell 61, which comprises anterior portion 62 and posteriorportion 63. Anterior portion 62 and posterior portion 63 can beintegral, or they can be separate components secured together.Identifier 75, which can include information identifying the implant, issecured to phone dial 73 after the inner bag is placed within shell 61.The implant also optionally includes at least one suture tab 64, whichcan be used to help secure the implant to tissue within the subject.Sutures can be used to secure the suture tabs to tissue within thepatient, thereby securing the implant within the patient. The suturetabs 64 can be secured to the implant after assembly with adhesive, suchas silicon adhesive.

In some embodiments the perimeter formed when the perimeters of anteriorportion 65 and posterior portion 72 are heat staked together can becomerigid and may cause discomfort when implanted. The embodiment in FIG. 5includes serpentine cuts in the perimeters of both anterior portion 65and posterior portion 72, which create the fingers described above, toreduce the amount of rigidity in this region. In some embodiments all ofthe fingers are heat staked together, while in some embodiments lessthan all of the fingers are heat staked. In some embodiments at leastone of the fingers is cut off or trimmed to reduce the stiffness of thefinger region.

In one or more exemplary embodiments, the components of the implantableportion can be made from the following materials: the outer shellcomprises silicone rubber; the suture tabs comprise silicone rubber withpolyester (Dacron) reinforcement; the inner bag is a barrier film; thehammock and the band are either polyethylene or barrier film; and thephone dial and the phone dial film are silicone rubber.

In the embodiments in which the fluid is CO₂, the inner bag provides abarrier to CO₂ after it has been released from the gas reservoir.

In some embodiments the inner bag or chamber is at least partially madefrom a non-elastic material and is pre-formed, such as, for examplewithout limitation, a breast shape with a lower pole extension. Theinner chamber will expand towards the anatomical shape (not necessaryreaching the exact preformed configuration) when the fluid is releasedfrom the reservoir into the internal chamber. This responds unlike aliquid-filled elastomeric balloon, which does not have a preformed shapeto which the balloon expands when filled with a liquid. When the innerbag has a preformed shape of a breast, the expanded shape emphasizeslower pole expansion where tissue generation is particularly desiredduring breast reconstruction so that the skin assumes the shape of abreast. FIGS. 2 and 5 are exemplary embodiments in which a substantiallyinelastic portion of the implant has a breast configuration or shape. Inparticular, in these embodiments the inner chamber comprises theinelastic component that has the general breast shape.

In some embodiments the inner bag comprises multiple layers of materialthat are sandwiched together to form the inner bag. Exemplary materialswhich may be utilized in the inner bag can be found in U.S. Pat. App.Pub. 2006/0069403, filed Sep. 21, 2005, which is incorporated herein byreference. In some embodiments the inner bag roughly has the thicknessof a piece of paper, and while it has the ability to stretch arelatively small amount, it does not have properties like an elasticfilm. To form the inner bag in a desired anatomical shape, any layerswhich make up the inner bag are positioned adjacent one another with thedesired layering, heated, applied to a mold which has the desired shape,and then allowed to cool on the mold. The mold is then removed. In theembodiment in FIG. 5, for example, any layers that make up anteriorportion 65 can be formed on a mold as described above.

A pre-formed configuration also prevents the expandable chamber fromexpanding into undesirable shapes since the inner bag will tend toexpand into its pre-formed shape. This is unlike, for example, a hot-dogshaped elastomeric balloon, which, if squeezed in the middle, willbecome a dog-bone shaped balloon. Forming the inner bag in the shape ofa breast, for example, prevents the implant from expanding laterally(under an arm) or superiorly (toward the clavicle). The shape of thetissue to be expanded can therefore be controlled by forming the innerbag into a particular shape.

In some embodiments the fluid source is a gas source, and in someembodiments the gas is, for example without limitation, CO₂. In someembodiments the gas reservoir has an internal volume of about 1 cc toabout 50 cc, and in some embodiments is about 2 cc to about 10 cc. In anexemplary embodiment, a compressed gas source has a total internalvolume of about 5 ml. Optionally a large tissue expansion may beachieved by providing about 2.5 grams of CO₂ in a 5 ml internal-volumecontainer. This provides about 1200 ml of CO₂ at 15.5 PSI (0.8 PSI aboveatmosphere at sea level). The exact amounts may vary, but in someembodiments a constant ratio can be used. For example, for every 1 mL ofinternal volume container filled with 0.5 grams of CO₂ gas, there isabout 240 mL final volume (at 0.8 PSI). The reservoir can be encased ina leak-free canister.

The outer shell generally provides a tissue interface for theimplantable device. In some embodiments the outer shell is comprised ofsilicone, but can be made of any other suitable material. It can besmooth, but in some embodiments the outer shell is textured to helpstabilize the implant within the patient. When the outer shell is asilicone outer shell, the silicone outer shell provides littleresistance to the permeation of CO₂.

The implantable portion of the tissue expansion system includes acommunication component, which can include an antenna, to facilitatecommunication with the remote controller. In some embodiments thecommunications component is secured to an anterior portion of the innerbag to provide for the easiest coupling between the remote controllerand the antenna when the remote controller is held close to thepatient's body in the region in which the implant is positioned. Forexample, in the embodiment in FIG. 2, communications component 25 issecured to the anterior portion of the inner bag. Communicationscomponent 25 is also secured to a superior portion of the inner bag,which can make it easier for the remote controller to communicate withthe communications portion of the implant.

FIG. 6 illustrates an exemplary implant 500, which includes inner bag502 (outer shell not shown) with a section removed to revealcommunications component 504 and driver 506, both of which are securedto inner bag 502. Implant 500 also includes suture tabs 508 (a third tabis not shown). In general, the inner bag has anterior and posteriorportions as indicated. In this embodiment, the posterior portiongenerally refers only to the backing, or the generally flat portion, ofthe inner bag. The curved portions of the inner bag are generallyconsidered the anterior portion. Additionally, the inner bag has aninferior portion and a superior portion as shown. The implant can beconsidered to be divided into 4 quadrants, based on the planesseparating the anterior/posterior portions and the superior/inferiorportions. As shown, the antenna is secured to the anterior portion andthe superior portion of the inner bag to make the coupling between theremote controller (not shown) and communication component 504 asefficient as possible.

In embodiments in which the inner bag has a pre-formed expandedconfiguration, the communication component is attached to a complex3-dimensional shape in which the inner bag is formed. The communicationcomponent, however, has the ability to deform the shape of the inner bagwhen secured thereto due to the weight and stiffness of thecommunication component. In some embodiments, in order to secure thecommunication component to the inner bag without altering the shape ofthe inner bag, the communication component is first encapsulated in afilm layer, which is then secured to the inner bag. During attachment ofthe encapsulated communication component, the formed membrane has theability to provide an approximately uniform amount of pressure over thecommunication component while it is attached to the inner bag. Amaterial such as an ESCAL™ bag can be used as the membrane to providethe necessary amount of pressure to the encapsulated communicationcomponent while being laminated to the inner bag. This will prevent theinner bag from losing its preformed shape. Additionally, thecommunication component is positioned on the anterior portion of theinner bag to maintain its position as close as possible to the surfaceof the patient. This improves the communication component'selectromagnetic coupling with the remote controller.

The implant also includes a driver, which comprises a fluid reservoirand a valve, which controls the flow of fluid from the reservoir. Insome embodiments the fluid reservoir is a compressed gas source.Actuation of the remote controller can open the valve to controllablyreleases gas from the reservoir into the inner chamber.

After the implantable portion is positioned within the patient, theremote controller is actuated to release the fluid from the fluidreservoir, through the valve, and into the inner chamber. A “burp” isreferred to herein as the event in which fluid is released from thereservoir. The periodic or continuous release of the fluid into theexpandable inner chamber causes the inner chamber to expand over time,which causes the expansion of tissue proximate the implant. Once thetissue has been expanded to the desired degree of expansion, the implantcan be removed from the patient and a permanent implant can replace thetemporary implant.

The remote controller is adapted to control the amount of fluid that isreleased from the fluid reservoir over time. When the user actuates theactuator on the remote controller, the valve within the driver opens andreleases the fluid, such as CO₂, from the reservoir into the expandableinner chamber.

The tissue expansion system comprises various electronic components toperform the functions described herein. The electronic components can bedisposed in the remote controller, the implant, or some of theelectronics can be disposed in the controller while some are disposed inthe implant. In general, the tissue expansion system includes electroniccomponents that allow the remote controller to wirelessly communicatewith the implant and provide power thereto to control the release offluid from the fluid reservoir. In some embodiments, such as thosedescribed above, the implant includes an antenna adapted to communicatewith the driver. The antenna is adapted to be electromagneticallycoupled with an antenna in the remote controller upon actuation of theremote controller such that actuation of the remote controller inducescurrent to flow through the solenoid coil to open the valve, therebyreleasing the fluid from the reservoir. In this manner the remotecontroller is adapted to provide power to the implantable implant viainductive coupling. In order to facilitate the transmission of temporarypower to the driver, the antenna of the external device and theimplantable devices must be in within a certain range of each other.Transmission of power between the remote controller and the implant canalternatively be carried out through a radiofrequency link or othertypes of wireless links.

In some embodiments the remote controller includes a power source, suchas a rechargeable battery, to provide power to some or all of thesystem's electronic components. The implantable portion may alsocomprise a power source to provide power to electronic components withinthe implantable portion.

In some embodiments the implantable fluid is CO₂, and the CO₂ will leakout of the inner bag/outer shell assembly over time. While the inner bagcan be adapted to provide for a CO₂ barrier, some CO₂ will diffusethrough the layers of the inner bag over time. CO₂ can diffuse throughthe molecular structure of polymers, and is essentially impossible tocompletely contain within polymeric material. To determine the level ofCO₂ permeability through an inner compartment, a known amount of CO₂ isreleased into an inner compartment, and the inner compartment issubmersed in saline. CO₂ will diffuse through the inner compartment overtime and into the saline. Periodic measurements of the volume of theinner compartment are made over time, which provides for an estimate ofthe rate of CO₂ permeation. In some embodiments the inner compartment ispermeable between about 0 and 3 mL/day.

FIGS. 7, 8A and 8B illustrate an exemplary embodiment of a portion of animplantable portion of a tissue expander system. The implantable portionincludes an antenna 414 that is movably secured to anterior panel 410 ofan expandable chamber. Anterior panel 410 generally defines at least aportion of the expandable chamber, and in this embodiment defines ananterior portion of the expandable chamber. Although not shown, anteriorpanel 410 is secured to a posterior panel, or backing, of the expandablechamber, as described herein. In this embodiment the antenna is adaptedto receive and/or send wireless signals with an external remotecontroller as described herein. The remote controller is actuated tocommunicate with the antenna, which activates the release of gas fromthe compressed gas reservoir, examples of which are described in moredetail herein. The antenna is secured to the anterior portion of theimplant to allow for easier communication with a remote controller dueto the shorter distance, but the antenna could also be secured to theposterior backing of the implantable portion as well.

In general, the expandable chamber of the implantable portion includes arelatively thin-walled portion, and an antenna secured to thethin-walled portion will generally be stiffer than the wall. When theimplant is manipulated by a physician during insertion, the physicianinherently manipulates and distorts the anterior panel to some degree.This creates loads on the antenna. Additionally, after implantation, theantenna undergoes loads as the inflatable chamber is inflated with gasfrom the compressed gas reservoir. There is thus a risk that the stifferantenna will damage the wall of the expandable chamber.

An implant that is configured to allow for some movement between theantenna and the expandable chamber to which it is secured willbeneficially reduce or eliminate damage to the wall. In the embodimentin FIGS. 7, 8A, and 8B, the antenna is movably secured to acommunication member 412, which in this embodiment has a general pocketconfiguration that includes two sides or portions in between which theantenna is movably disposed. The communication member similarly issecured to the anterior panel 410 of the expandable chamber in such away that there is some movement that can occur between the communicationmember and the expandable chamber. In this embodiment there are thus twoways in which relative movement between components creates a reducedrisk of damage to the expandable chamber to which the antenna issecured.

The following provides an exemplary method of assembling the anteriorpanel and communication component subassembly shown in FIGS. 7, 8A, and8B. The steps need not be carried out in the specific order, and somesteps may be left out of the method if the method is modified such thatthe steps are optional. An antenna pocket is first created by bonding afilm ring between two film discs. In FIG. 7 the bonds are indicated bythe darkened region 416. A portion of the antenna pocket is then bondedto anterior panel 410 at bond locations 417, 418, and 419. Antenna 414is then inserted into the antenna pocket and bonds are formed betweenthe two sides at discrete locations 420-422. Bonding of the pocket isthen completed by bonding the antenna pocket (with antenna therein) toanterior panel 410, this time at locations 420, 421, and 422. More orfewer bonding locations can be used. The antenna is disposed within thepocket and is able to float within the antenna pocket. Additionally, thepocket is attached directly to the inside of the expandable chamber at aplurality of discrete locations rather than all the way around theperiphery of the pocket. The areas where the pocket is not directlysecured to the expandable chamber allow for some movement between theantenna pocket and the expandable chamber wall, allowing for less stressin the expandable chamber, and reducing the likelihood of damage to theexpandable chamber wall. In this embodiment the antenna is movablysecured to both the communication component 412 and the wall of theexpandable chamber 410.

As set forth above, anterior panel 410 and communication component 412are components of an implantable portion of a tissue expansion system,and can be incorporated into any of the tissue expander systemsdescribed herein.

FIG. 7 is an exploded view showing communication component 412 andanterior panel 410 before they are coupled together. The anterior “A”and posterior “P” directions are indicated, and reflect the relativepositioning of the device as would be positioned within a patient'sbreast. Inferior “I” and superior “S” directions are also indicated.FIGS. 8A and 8B are assembly views, with FIG. 8B being from the sameperspective as FIG. 7. FIG. 8A is from a generally superior and anteriorview.

In some embodiments the fluid that is used to expand the expandablechamber is a gas, such as from a compressed gas source. A gas source canbe external to the patient, positioned within the patient and outsidethe expandable chamber, inside the expandable chamber, or partiallyinside and partially outside the expandable chamber. It may bebeneficial to have, in addition to the expandable chamber layer (whichmay be referred to herein as a wall or surface), a second wall (orlayer) disposed outside of the expandable chamber layer and adjacent tothe expandable chamber wall that helps act as a gas barrier layer toreduce the gas permeation rate out of the expandable chamber. Reducingthe permeation, if desired, can be a significant advantage in thatinflation of the inflatable chamber is much more controlled andreliable. Gas permeation out of the chamber can, without a correspondingamount of new gas being released into the inflatable chamber, reduce theoverall inflation of the inflatable chamber and can thus slow or preventthe desired tissue expansion. By reducing permeation the inflation andthus tissue expansion (e.g., pocket creation) can be controlled in amuch more reliable manner. An added layer or wall outside of theexpandable chamber wall can provide that significant advantage.Additional considerations for gas permeability and material selectioncan be found herein.

FIG. 9 is an exploded view of an exemplary inner portion, or inner bag,430 of an implantable portion of an exemplary tissue expander system.Inner portion 430 can be used with any of the tissue expanders systemsdescribed herein. In some embodiments inner portion 430 is positionedinside an outer shell, such as an elastic outer shell, examples of whichare described herein. Inner portion 430 includes a posterior portion 440and an anterior portion that includes anterior inner layer 450 andanterior outer layer 470. “Inner layer” 450 and “outer layer” 470 may bereferred herein as an “inner member” and an “outer member.” Both theinner member 450 and the outer member 470 are deformable. Posteriorportion 440 includes backing 441 secured to driver assembly 442,examples of which are described herein. In some embodiments anteriorinner layer 450 includes anterior panel 410 and communication component412 shown in FIGS. 7, 8A, and 8B. In this embodiment inner layer 450 isa deformable member comprising an inelastic material 452 that is moldedto have a pre-formed configuration (e.g., a breast configuration with alower pole extension) and is adapted to be reconfigured towards thepre-formed configuration when the inflatable chamber is inflated withgas from the compressed gas reservoir. Exemplary methods of forming theinelastic material into a desired pre-formed configuration such as theconfiguration with the lower pole extension are described herein.Inelastic member 452 can in some embodiments be comprised of multipleplies of a multi-layer barrier film with the outer layers beingpolyethylene, which enables heat sealing/staking with other polyethylenecomponents, and the barrier material can be PVDC (polyvinylidenechloride). Anterior outer layer 470 includes inelastic member 471 whichis in some embodiments a single ply of a multi-layer barrier film withthe outer layers being polyethylene, which enables heat sealing/stakingwith other polyethylene components. Inelastic element 471 is in thisembodiment also pre-formed with a, for example without limitation,general breast configuration with a lower pole extension in the samemanner as is inelastic element 452. In some embodiments inelasticelement 471 includes PVDC, and thus can include the same material as ininelastic element 452. The two inelastic elements need not be the samematerial, however, nor do they need to have the same general pre-formedconfiguration if they both do have pre-formed configurations. Anteriorouter layer 470 is secured to anterior inner layer 450 by heat stakingat the outer perimeter 454. Anterior inner layer 450 is secured toposterior portion 440 by heat staking at the outer perimeter 443. Inthis embodiment both the inner and outer members comprise inelasticmaterials with pre-formed configurations that are generally the same, ascan be seen from FIG. 9. By having two (or more) layers in the innerportion as shown by the two members 450 and 470 in FIG. 9, permeation ofthe gas out of the inner portion is significantly reduced.

Outer member 470 can also provide additional benefits. In some uses,tissue that is adjacent the implant, can, without an outer member, causethe inner member to fold in certain places. For example, if the implantis placed sub-muscular, the muscle moving over the implant can causerolling folds in the inner member. Erosion or damage of the material canoccur over time at the location of the folds, possibly causing the innermember to rupture or exhibit increased permeation in the case of a gasfilled implant. An outer member, such as outer member 470, can thus actas a relatively lower friction interface so that as tissue adjacent theimplant moves the outer member can move relative the inner member,reducing the amount of moving that occurs in the inner member. Damagingfolding and/or erosion in the inner member are thereby reduced. Reducingthe movement and folding that occurs in the inner layer by incorporatingan outer layer can thus protect the inner layer's integrity and reducethe likelihood of damage and rupture.

Having an outer member or layer disposed outside of a chamber can alsobe beneficial even if the fluid inside the chamber is not a gas, andeven if the chamber is not filled with fluid from a fluid source. Forexample, an outer layer added to a silicone filled breast implant couldprovide advantages over a single filled chamber. As described herein,erosion or damage of the material can occur over time at the location ofthe folds in the inner member, possibly causing the inner member torupture. This outer member can act as a relatively lower frictioninterface so that as tissue adjacent the implant moves the outer membercan move relative the inner member, reducing the amount of moving thatoccurs in the inner member reducing the damaging effect of folds. Insome embodiments the outer layer, such as outer layer 471, has athickness that is less than a thickness of inner layer, such as innerlayer 452. By having a thickness in the outer layer that is less than athickness of the inner layer, the outer layer can be folded with lessdamage to the outer layer. It also moves more easily in response toadjacent tissue (e.g., muscle) movement, and the tissue movement is lesslikely to drag a section of folded inner member with it. The outermember is thus both less likely to be damaged when folded and to damagethe inner member in response to tissue movement.

In some of the embodiments herein the inner layer is between about 75microns and about 150 microns thick, and the outer layer is betweenabout 25 microns and about 75 microns thick. In some embodiments theinner layer is between about 75 microns and 100 microns thick. In someembodiments the thickness of the inner layer is greater than thethickness of the outer layer. In some embodiments the thickness of theinner layer is at least 1.5 times the thickness of the outer layer(e.g., 50 microns thickness outer and 75 microns thickness inner). Insome embodiments the thickness of the inner layer is at least 1.75 timesthe thickness of the outer layer. In some embodiments the thickness ofthe inner layer is at least 2 times the thickness of the outer layer(e.g., 50 microns thickness outer and 100 microns thickness inner). Insome embodiments the inner layer is no more than 8 times the thicknessof the outer layer (e.g., 25 microns thickness outer and 200 micronsthickness inner). In some embodiments the inner layer is no more than 6times the thickness of the outer layer.

In some embodiments the outer layer can be an elastic component andstill provide the benefits described above about reducing erosion to theinner layer. Thus in some embodiments the inner layer can include aninelastic material with a pre-formed configuration and the outer layercan be an elastic material.

In some embodiments a standard known gel-filled breast implant with anelastic material that defines the chamber in which the gel is disposedcan be modified to include an outer layer around at least a portion ofthe implant. For example, the outer layer could extend around the entireimplant or could extend around only an anterior portion.

In embodiments that include an outer layer or outer member (e.g., outermember 470) outside the inner member (e.g., inner member 450) alubricious material can be added between the two members to reducefriction between the two members and thus reduce the likelihood ofdamage to the inner and outer members. As stated above, the inner andouter members can move relative one other when adjacent tissue moves,which advantageously protects the inner member. A lubricious materialbetween the two members, however, reduces undesired rubbing between thetwo members, which can also lead to erosion and possibly rupture.

In an exemplary method of manufacturing, prior to bonding anterior outerlayer 470 to anterior inner layer 450, a lubricious material 460 isplaced or positioned between anterior outer layer 470 and anterior innerlayer 450 resulting in increased wear resistance for friction andrubbing on the implant. The lubricious material is generally abiocompatible lubricant, for example without limitation, a siliconebased lubricant or other biocompatible lubricant (e.g., NUSIL MED-420,100 cP viscosity). Other lubricants (biocompatible) and viscosities maybe used. Another example of a lubricious material that can be used issoybean oil. Additionally, the lubrication could be provided by acoating on one or both of the inner and outer members. The lubricioussubstance advantageously reduces shear between the anterior inner member450 and anterior outer member 470. Alternatively, a material that maynot be typically considered lubricious could also reduce the frictionbetween the inner and outer members, such as sterilized saline or water.In the embodiment in FIG. 9, the lubricious material is contained in achamber, at least part of which is disposed directly between the innerand outer members.

The volume of lubricant can depend on the size of the tissue expanderand its intended use, but exemplary volumes that can be placed betweenlayers (or members) of exemplary breast tissue expanders can be fromabout 0.2 mL to about 2 mL, or between about 0.5 mL to about 1.5 mL. Forexample, in some specific embodiments the volume is about 0.8 mL ±0.2,1.0 mL ±0.2, or about 1.2 mL ±0.2. In general, the volume of lubricantis not intended to add thickness to the inner portion of the tissueexpander (the thickness being measured between the inner surface of theexpandable chamber and the outer surface of the outer member) butinstead is used to provide a thin lubricating film. While there will besome marginal thickness added, the addition of lubricant is intendedherein to substantially not change the thickness at all.

A traditional breast implant could be enhanced with a lubricous materialas well. For example, in some embodiments a breast implant has anelastic material that defines a chamber in which a gel is disposed. Thebreast implant can also include an outer member that can be an elasticlayer, and a lubricous material can be positioned between the inner andouter layers to reduce friction between the inner and outer members.

In some situations gas that has been released into the inflatablechamber will, over time, permeate out of the inflatable chamber. Thiscan prevent the inflatable chamber from maintaining a desired expansionpressure on tissue adjacent the implant. In some embodiments the gasreservoir, which can be a CO₂ reservoir, is adapted such that itinitially contains more compressed gas than the inflatable chamber isadapted to maintain. If an amount of gas above a certain thresholdpermeates out of the chamber, or if the internal chamber pressure dropsbelow a certain threshold (or some other measured event occurs), thesystem is adapted to allow additional compressed gas to be released fromthe reservoir. This ensures that the implant maintains a desiredpressure and thus tissue is expanded as expected.

In some embodiments the system has preset limitations to prevent theuser from using the system in certain ways. For example, as set forth inat least U.S. application Ser. No. 12/973,693, filed Dec. 20, 2010, thesystem can be adapted to prevent the patient from releasing too muchcompressed gas without a given period of time. The system can also beadapted to prevent the release or more than a given total amount of gasfrom the reservoir. In some embodiments the system is adapted so thatthe preset limitations can be overridden. For example, a physician canuse the master key to reprogram the remote controller to override thepreset parameters.

U.S. application Ser. No. 12/973,693 describes a system in which therelease of gas from the gas reservoir occurs when the valve in the valveassembly is opened in response to an electrical signal from the antenna(which responds to actuation of the remote controller). In someembodiments the dosing occurs (i.e., the valve is opened) is response tothe application of a relatively strong external magnetic field. In someembodiments the physician or patient uses a magnet or electromagnetplaced in proximity to the implant to open the valve and release gas.Application of the external magnetic field can be used intermittently inthe same manner in which the remote dosage controller is actuated. Theexternal magnetic field could be applied in situations where there is acommunication failure between the implant and the remote controllerwithout having to remove the implant from the patient.

In some situations a fluid such as a gas can become trapped between theinner anterior panel and the exterior shell. This can occur when gaspermeates through the anterior panel. In some embodiments the exteriorshell, such as an elastic exterior shell, has one or more aperturesthrough it that prevent air from being trapped.

Holes can also be made in the external shell to allow perfusion of fluidthere through. For example, holes can be used in drug delivery methodsto deliver chemotherapeutic agent, antibiotics, etc., to site specificlocations. For example, nearly all chemotherapeutic agents have a lowtherapeutic index. Due to the limited efficacy of most chemotherapeuticagents against the majority of solid tumors, it is desirable to increasethe concentration and total dose of drug to the tumor bed than can besafely achieved by a systemic infusion. The space between the inner bagand outer shell provides an ideal location to place a bolus ofchemotherapeutic agent intended for regional chemotherapy. Achemotherapeutic agent is locally dispersed through the vent holes inthe outer shell.

In some embodiments a dedicated fluid agent reservoir is disposedbetween the anterior panel and the exterior shell. After implantation,the fluid agent is locally dispersed through vent holes in the outershell.

In some embodiments the outer shell and/or inner layers are coated orimpregnated with an antimicrobial or multiple substances. For devices inwhich the outer shell is not a fluid barrier, it can be constructed toprovide antimicrobial or other therapeutic benefit.

In some of the embodiments herein there is a single remote dosagecontroller that is synched up with a single implant. In some embodiment,however, a single remote dosage controller is adapted to control aplurality of implants. Each of the implants can be implanted indifferent patients, or multiple implants can be implanted in a singlepatient. Each of the implants can have its own preset parameters or theimplants can have the same preset parameters. The remote controller isadapted to store the parameters for each of the implants.

In some embodiments the system is adapted to provide one or moreindications to the patient or other user, such as a physician. Theindications convey one or more types of information to the physicianand/or patient. The remote dosage controller or other remote device isadapted to provide the information. In some embodiments the informationis communicated to the user via an interface on the remote dosagecontroller. The interface can include any number of known outputs tocommunicate the information. For example, the remote dosage controllercan have an LCD screen that indicates one or more type of informationabout the system. In other embodiments a plurality of LED can be used toprovide information to the user.

In some embodiment the system includes an indicator that communicates toa user the level of inflation of the inflatable chamber. The indicatorcan communicate the pressure in the inflatable chamber, how much gas hasbeen released from the gas reservoir, or provide an indication of howfull the inflatable chamber is as a percentage of a maximum level ofinflation. For example, an LCD screen could indicate with icons or barsthe level of inflation. The indicator could also be a numericalindication, indicating a pressure, volume of gas released, or percentfull.

In some embodiments the indicator communicates the amount of gasremaining in the gas reservoir. For example, the remote dosagecontroller can include a screen with a number of bars that indicate howmuch gas remains, similar to a battery life indicator on a smartphone.

In some embodiments the indicator communicates information indicative ofthe most recent dose, or a time history of doses. For example, theindicator can communicate when or how much gas was released in the mostrecent dose. The indicator can be a numerical indicator on a LCD screenthat provides a time, for example, of the most recent dose.

In some embodiments the system includes an indicator that provides analert to the user. The remote controller, or a handheld device like asmartphone that is in communication with system, can have the indicatorthat is adapted to provide an alert. The alert can be a reminder alertthat reminds the user to administer a dose. For example, if a certainperiod of time has passed without dosing, the system is adapted togenerate an alert, such as a visual alert (e.g., blinking LED, iconflashing on an LCD screen), audio alert (e.g., beeping sound), or atactile alert (e.g., vibration) to the user. The alert can occur on theremote dosage controller, such as an illuminated LED or a beep generatedby an audio system. In some embodiments the remote dosage controllersends an output to a remote device such as a smartphone when an eventhas triggered the alert. The handheld device can provide the alert tothe user. For example, the smartphone can vibrate or emit a certainringtone to communicate the alert to the user. Any number of suitablealerts can be communicated to a user in this manner. Other indicatorscan be provided with the alert. For example, if there is an alert thatdosing has not occurred for a given period of time, the alert can beaccompanied with a visual indication (e.g., numerals) of when the lastdosage occurred.

The remote dosage controller (or other remote device) can include aninterface that allows the user to interact with the device. For example,the remote controller can include a touchscreen or buttons that allowsthe user to access information indicative of the system. As an example,the user can view a listing of the times of previous doses by accessingthis information via the interface.

The system interface can also be adapted to allow the user (e.g.,patient) to send a request to a physician to review and/or modify thesystem parameters remotely. For example, if a patient notices excessivepermeation and the patient wishes that the physician override the systemparameters to allow more gas to be released that would be allowed underthe preset parameters, the patient can actuate the remote dosagecontroller (or other remote device) to send a notification to thephysician. This can prompt the physician to review the status of theimplant (e.g., percent full, the amount of gas released, internalpressure, etc.) and perhaps other patient information to determine ifthe parameters can be overridden or if there should be an office visit.The physician can then remotely send a communication to the remotecontroller that changes, by overriding, one or more parameters of thesystem.

The systems described herein and in the applications incorporated byreference use very little energy to release the gas from the gasreservoir into the inflatable chamber. One advantage of this is thatbatteries are not required onboard the implant. Less than 20 milliwattsare used during dosing. The remote dosage controller includes batteriesto power the operation.

In some embodiments the implant includes one or more internal sensors tosense or more implant conditions. For example, the implant can include apressure sensor that senses internal pressure within the inflatablechamber. This can provide an indication of how much expansion has takenplace within the implant. In these embodiments the remote dosagecontroller can include an interface that provides an indication of theinternal pressure. The status of the internal pressure can be used incombination with the alerts provided herein.

In some embodiments the system includes a proximity sensor that can beused to detect the proximity of a target on the implant and a sensor inthe remote dosage controller. The target can be on the anterior portionof the implant, such as on the anterior panel or on the communicationcomponent. The sensor detects the proximity of the target, whichprovides an indication of how much expansion of the chamber hasoccurred.

The systems described herein and in the applications incorporated byreference are advantageous to previous attempts in that there issubstantially less pain (if any) associated with the tissue expansion.One of the factors that provides this benefit is that the systems hereinexpand the inflatable chamber on more continuous basis than previousattempts, which administer boluses of fluid. This allows for moregradual, step-wise, inflation, which reduces pain and discomfort.Another significant advantage of the relatively continuous expansion isthat the time to full expansion is substantially less. The systemsdescribed herein can expand tissue and create a pocket in about 15 days,as opposed to previous attempts that can take as much as 6 weeks.

What is claimed is:
 1. A tissue expander comprising: an implantableportion comprising a fluid source in communication with an expandablechamber, wherein the expandable chamber includes an anterior portion anda posterior portion, wherein the anterior portion includes a firstdeformable member and a second deformable member, wherein the firstdeformable member is disposed within the second deformable member,wherein the first deformable member has a thickness that is greater thana thickness of the second deformable member, and wherein the fluidsource is secured to the posterior portion, wherein the implantableportion further comprises a communication component that comprises afloating antenna, the communication component secured to an innersurface of the first deformable member, the antenna configured forwireless communication with an external controller, wherein thecommunication component is in operable communication with the fluidsource.
 2. The tissue expander of claim 1 wherein the first deformablemember at least partially defines the expandable chamber.
 3. The tissueexpander of claim 2 wherein the second deformable member is configuredas a barrier layer to the fluid.
 4. The tissue expander of claim 1further comprising an outer shell disposed at least partially around thefirst and second deformable members.
 5. The tissue expander of claim 4wherein the outer shell is an elastic shell.
 6. The tissue expander ofclaim 1 wherein the first deformable member has a preformedconfiguration.
 7. The tissue expander of claim 6 wherein the firstdeformable member comprises an inelastic material with the pre-formedconfiguration.
 8. The tissue expander of claim 6 wherein the seconddeformable member has a preformed configuration.
 9. The tissue expanderof claim 8 wherein the first and second deformable members havepre-formed configurations that are the same.
 10. The tissue expander ofclaim 1 wherein the first and second deformable members are thin-walleddeformable members.
 11. The tissue expander of claim 10 wherein thefirst deformable member has a thickness between about 75 microns andabout 150 microns.
 12. The tissue expander of claim 11 wherein thesecond deformable member has a thickness between about 25 microns andabout 75 microns.
 13. The tissue expander of claim 10 wherein the seconddeformable member has a thickness between about 25 microns and about 75microns.
 14. The tissue expander of claim 1 wherein at least one of thefirst and second deformable members comprises multiple layers ofmaterial secured together.
 15. The tissue expander of claim 1, furthercomprising a lubricious material disposed between the first and seconddeformable members to reduce friction between the first and seconddeformable members, wherein the lubricious material has a viscosity ofat least 50 cP.
 16. The tissue expander of claim 15 wherein thelubricious material is a biocompatible lubricant.
 17. The tissueexpander of claim 16 wherein the biocompatible lubricant is asilicone-based lubricant.
 18. The tissue expander of claim 15 whereinthe volume of lubricious material disposed between the first and secondmembers is between about 0.5 mL and about 2.5 mL.
 19. The tissueexpander of claim 18 wherein the volume of lubricious material disposedbetween the first and second members is between about 0.5 mL and about2.0 mL.
 20. The tissue expander of claim 15 wherein the lubriciousmaterial comprises a coating on at least one of the two members.
 21. Thetissue expander of claim 15 wherein the lubricous material providessubstantially no additional thickness to the implantable portion. 22.The tissue expander of claim 1 wherein the first deformable members isattached directly to the second deformable member.
 23. The tissueexpander of claim 22 wherein the first and second deformable members aresecured to each other at respective peripheries of the first and seconddeformable members.
 24. The tissue expander of claim 1 wherein theexpandable chamber includes a posterior backing coupled to the firstdeformable member.
 25. The tissue expander of claim 1 further comprisingan external controller adapted to be in communication with theimplantable portion to enable fluid to be released from the fluid sourceinto the expandable chamber.